It is known that sleep disturbances in healthy youth have negative effects on neurobehavioral functioning. Further, data support that individuals with diabetes have more sleep disturbances and compromised neurobehavioral functioning than individuals without diabetes. However, the joint impact of sleep and glucose on neurobehavioral functioning in youth with type 1 diabetes (T1DM) is not yet known. Therefore, our primary study aims are to: (1) determine the relative contributions of various sleep disturbances on glucose control in youth with T1DM; (2) examine the joint impact of glucose control and sleep disturbances on neurobehavioral outcomes in youth with T1DM; and (3) determine if increasing sleep duration relative to youth's typical schedules contributes to changes in glycemic control and neurobehavioral performance. These aims will be achieved by following 120 youth with T1DM ages 10 through 16 for six days of naturalistic sleep using polysomnography, actigraphy, and questionnaires to assess sleep; continuous glucose monitors and hemoglobin A1C values to assess glucose control; and standardized cognitive tasks and behavior rating scales to assess neurobehavioral functioning. Further, the proposed study is innovative in that it will extend existing research by moving from correlational findings to an experimental paradigm by randomizing youth with T1DM to either a Sleep Extension or Fixed Sleep Duration condition for an additional six days. Once our aims are achieved and a causal link is established, the proposed Sleep Extension intervention will advance knowledge about the role of sleep in diabetes management and provide a beneficial intervention to help youth with T1DM.